The inventive concepts disclosed herein relate generally to the field of high frequency (HF) communication systems. More particularly, embodiments of the inventive concepts disclosed herein relate to systems and methods for resilient HF linking.
HF communication provides a low cost approach for communicating over long distances, e.g., beyond the horizon. HF communication systems operate at frequency bands between 2 megahertz (MHz) and 30 MHz. Within this frequency range, propagating HF radio waves can bounce off ionospheric layers, land or sea allowing for long distance (or beyond the horizon) communication. Specifically, HF radio waves can travel long distances (e.g., beyond line of sight) while bouncing back and forth between the ionospheric layers and land (or sea). Compared to, for example, satellite communication, HF communication is significantly less costly.
A drawback associated with HF communication is that HF channels (or HF radio links) are typically time varying, unpredictable, and prone to fading and noise. In particular, HF ionospheric propagation conditions can change significantly over time resulting in time-varying characteristics (e.g., impulse response, center frequency, background noise, etc.) of HF channels. For instance, the structure of the ionospheric layers changes between day time and night time. Also, weather conditions (e.g., sun, rain, storms, lightning) can affect ionospheric absorption (or signal attenuation) and/or background noise. The time varying nature of ionospheric propagation conditions can impose limitations on the use of HF communication.